<?php

interface field
{
   public function normalizeValue($value, $lang = null);
   public function getFieldHTML($data);
   public function validateInput($value, $objectData);
   public function sweep();
}

interface Observable
{
  public function addObserver(Observer $observer);
  public function removeObserver(Observer $observer);
  public function fireEvent($msg = NULL);
}

interface Observer
{
  public function notify($args);
}